There are numerous types of vehicle brake systems, including those that include hydraulically actuated disk brakes. In such a system, engagement of a brake pedal by a driver causes a hydraulic piston to actuate a caliper out at the wheel that pinches a rotor between a pair of brake pads. The caliper carries the brake pads which frictionally interact with the spinning rotor and slow it down according to a number of factors, including the coefficient of friction (μ) of the materials.
The coefficient of friction (μ) of a brake pad and/or a rotor can be affected by the temperature of the system, as well as the humidity of the surrounding atmosphere. When a vehicle is stationary during extended periods of high humidity, moisture can cause rotor corrosion or alter the transfer layer properties which can increase the coefficient of friction (μ) and make the brake pads grab the rotor in a more aggressive way; this condition is sometimes referred to as ‘grabbing’. If the brake pad and/or the rotor is dry due to low-moisture or low-humidity conditions, then the coefficient of friction may decrease so that the brakes react in a less aggressive fashion. In some instances, the increased and/or decreased coefficients of friction are noticeable to the driver and are, thus, undesirable.